PHYSICAL LAYER METRICS TO SUPPORT ADAPTIVE STATION-DEPENDENT CHANNEL STATE INFORMATION FEEDBACK RATE IN MULTI-USER COMMUNICATION SYSTEMS

• US 20110069629A1
• Filed: 09/17/2010
• Published: 03/24/2011
• Est. Priority Date: 09/22/2009
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Breit, Gregory Alan, Abraham, Santosh Paul, Vermani, Sameer, Sampath, Hemanth
• Granted Patent: US 8,811,200 B2
• Time in Patent Office: Days
• US Class Current: 370/252
• CPC Class Codes: H04B 17/24 with feedback of measurements to the transmitter
• CPC Class Codes: H04B 17/336 Signal-to-interference ratio [SIR] or carrier-to-interference ratio [CIR]
• CPC Class Codes: H04B 7/0626 Channel coefficients, e.g. channel state information [CSI]
• CPC Class Codes: H04L 1/0027 Scheduling of signalling, e.g. occurrence thereof
• CPC Class Codes: H04L 25/0202 Channel estimation

Abstract

Certain aspects of the present disclosure present physical layer metrics for supporting adaptive station-dependent channel state information feedback rate in multi-user communication systems. For certain aspects, the physical layer metrics may be calculated at the stations and communicated to the AP. For certain aspects, the metrics may be calculated at an access point utilizing information about channel characteristics of stations available at the access point.

Claims

1. A method for wireless communications by a first apparatus, comprising:

obtaining a current channel estimate;

obtaining a recent channel estimate that was communicated to a second apparatus; and

calculating a first metric based at least on the current channel estimate or the recent channel estimate, wherein the first metric is used for determining whether a channel state information (CSI) update is to be sent to the second apparatus.

2. The method of claim 1, further comprising:

receiving a request message from the second apparatus; and

in response to the request message, transmitting the first metric to the second apparatus.

3. The method of claim 1, further comprising:

deciding to transmit the CSI update to the second apparatus based, at least in part, on the first metric and a predetermined criteria.

4. The method of claim 3, wherein deciding to transmit the CSI update comprises:

calculating a second metric based on signal to noise ratio (SNR) of a channel and the first metric; and

deciding if the CSI update should be sent to the second apparatus based on the second metric.

5. The method of claim 4, further comprising:

transmitting the second metric to the second apparatus.

6. An apparatus for wireless communications, comprising:

an estimator configured to obtain a current channel estimate, wherein

the estimator is also configured to obtain a recent channel estimate that was communicated to another apparatus; and

a circuit configured to calculate a first metric based at least on the current channel estimate or the recent channel estimate, wherein the first metric is used for determining whether a channel state information (CSI) update is to be sent to the other apparatus.

7. The apparatus of claim 6, further comprising:

a receiver configured to receive a request message from the other apparatus; and

a transmitter configured to transmit, in response to the request message, the first metric to the other apparatus.

8. The apparatus of claim 6, further comprising:

another circuit configured to decide to transmit the CSI update to the other apparatus based, at least in part, on the first metric and a predetermined criteria.

9. The apparatus of claim 8, wherein the other circuit is also configured to:

calculate a second metric based on signal to noise ratio (SNR) of a channel and the first metric; and

decide if the CSI update should be sent to the other apparatus based on the second metric.

10. The apparatus of claim 9, wherein the transmitter is also configured to transmit the second metric to the other apparatus.

11. An apparatus for wireless communications, comprising:

means for obtaining a current channel estimate;

means for obtaining a recent channel estimate that was communicated to another apparatus; and

means for calculating a first metric based at least on the current channel estimate or the recent channel estimate, wherein the first metric is used for determining whether a channel state information (CSI) update is to be sent to the other apparatus.

12. The apparatus of claim 11, further comprising:

means for receiving a request message from the other apparatus; and

means for transmitting, in response to the request message, the first metric to the other apparatus.

13. The apparatus of claim 11, further comprising:

means for deciding to transmit the CSI update to the other apparatus based, at least in part, on the first metric and a predetermined criteria.

14. The apparatus of claim 13, wherein the means for deciding to transmit the CSI update comprises:

means for calculating a second metric based on signal to noise ratio (SNR) of a channel and the first metric; and

means for deciding if the CSI update should be sent to the other apparatus based on the second metric.

15. The apparatus of claim 14, further comprising:

means for transmitting the second metric to the other apparatus.

16. A computer-program product for wireless communications by a first apparatus, comprising a computer-readable medium comprising instructions executable to:

obtain a current channel estimate;

obtain a recent channel estimate that was communicated to a second apparatus; and

calculate a first metric based at least on the current channel estimate or the recent channel estimate, wherein the first metric is used for determining whether a channel state information (CSI) update is to be sent to the second apparatus.

17. A wireless node, comprising:

at least one antenna;

an estimator configured to obtain a current channel estimate, wherein

the estimator is also configured to obtain a recent channel estimate that was communicated to an access point; and

a circuit configured to calculate a first metric based at least on the current channel estimate or the recent channel estimate, wherein the first metric is used for determining whether a channel state information (CSI) update is to be sent via the at least one antenna to the access point.

18. A method for wireless communications, comprising:

obtaining a current channel estimate and a recent channel estimate from an apparatus; and

calculating a first metric based at least on the current channel estimate or the recent channel estimate, wherein the first metric is used for determining whether a channel state information (CSI) update is to be requested from the apparatus.

19. The method of claim 18, further comprising:

deciding to request the CSI update from the apparatus based, at least in part, on the first metric and a predetermined criteria.

20. The method of claim 19, wherein deciding to request the CSI update is based at least on the first metric and time elapsed since a most recent CSI update.

21. The method of claim 19, wherein deciding to request the CSI update comprises:

calculating a second metric based on signal to noise ratio (SNR) of a channel and the first metric; and

deciding if a channel state information request should be sent to the apparatus based at least in part on the second metric.

22. The method of claim 21, wherein deciding comprises:

deciding if the channel state information request should be sent to the apparatus based at least on the second metric and time elapsed since a most recent CSI update.

23. The method of claim 19, further comprising:

transmitting, to the apparatus based on the decision, a request for the CSI update.

24. The method of claim 23, wherein the request for the CSI update comprises at least one of a training request message or a channel sounding message.

25. An apparatus for wireless communications, comprising:

a receiver configured to obtain a current channel estimate and a recent channel estimate from another apparatus; and

a circuit configured to calculate a first metric based at least on the current channel estimate or the recent channel estimate, wherein the first metric is used for determining whether a channel state information (CSI) update is to be requested from the other apparatus.

26. The apparatus of claim 25, further comprising:

another circuit configured to decide to request the CSI update from the other apparatus based, at least in part, on the first metric and a predetermined criteria.

27. The apparatus of claim 26, wherein deciding to request the CSI update is based at least on the first metric and time elapsed since a most recent CSI update.

28. The apparatus of claim 26, wherein the other circuit is also configured to:

calculate a second metric based on signal to noise ratio (SNR) of a channel and the first metric; and

decide if a channel state information request should be sent to the other apparatus based at least in part on the second metric.

29. The apparatus of claim 28, wherein the other circuit is also configured to:

decide if the channel state information request should be sent to the other apparatus based at least on the second metric and time elapsed since the last CSI update.

30. The apparatus of claim 26, further comprising:

a transmitter configured to transmit, to the other apparatus based on the decision, a request for the CSI update.

31. The apparatus of claim 30, wherein the request for the CSI update comprises at least one of a training request message or a channel sounding message.

32. An apparatus for wireless communications, comprising:

means for obtaining a current channel estimate and a recent channel estimate from another apparatus; and

means for calculating a first metric based at least on the current channel estimate or the recent channel estimate, wherein the first metric is used for determining whether a channel state information (CSI) update is to be requested from the other apparatus.

33. The apparatus of claim 32, further comprising:

means for deciding to request the CSI update from the other apparatus based, at least in part, on the first metric and a predetermined criteria.

34. The apparatus of claim 33, wherein deciding to request the CSI update is based at least on the first metric and time elapsed since a most recent CSI update.

35. The apparatus of claim 33, wherein the means for deciding to request the CSI update comprises:

means for calculating a second metric based on signal to noise ratio (SNR) of a channel and the first metric; and

means for deciding if a channel state information request should be sent to the other apparatus based at least in part on the second metric.

36. The apparatus of claim 35, wherein the means for deciding comprises:

means for deciding if the channel state information request should be sent to the other apparatus based at least on the second metric and time elapsed since a most recent CSI update.

37. The apparatus of claim 33, further comprising:

means for transmitting, to the other apparatus based on the decision, a request for the CSI update.

38. The apparatus of claim 37, wherein the request for the CSI update comprises at least one of a training request message or a channel sounding message.

39. A computer-program product for wireless communications, comprising a computer-readable medium comprising instructions executable to:

obtain a current channel estimate and a recent channel estimate from an apparatus; and

calculate a first metric based at least on the current channel estimate or the recent channel estimate, wherein the first metric is used for determining whether a channel state information (CSI) update is to be requested from the apparatus.

40. An access point, comprising:

at least one antenna;

a receiver configured to obtain via the at least one antenna a current channel estimate and a recent channel estimate from a wireless node; and

a circuit configured to calculate a first metric based at least on the current channel estimate or the recent channel estimate, wherein the first metric is used for determining whether a channel state information (CSI) update is to be requested from the wireless node.